问ValueError:在put请求/查找字段中不能将整数赋值给外键作为外键子字段

EN

class Member(BaseModel):

    objects = models.Manager()
    user = models.ForeignKey('api_backend.User', db_index=True, on_delete=models.CASCADE)
    cluster = models.ForeignKey('api_backend.Cluster', on_delete=models.CASCADE)

lass MemberPutRetrieveUpdateDeleteView(PutAsCreateMixin, MultipleFieldLookupMixin, generics.RetrieveUpdateDestroyAPIView):
    queryset = api_models.Member.objects.all()
    permission_classes = [permissions.IsAuthenticated, IsMemberOrKickMembers]
    lookup_fields = ['user', 'cluster']

    def get_serializer_class(self):
        if self.request.method in ['PUT']:
            return api_serializers.PartialMemberSerializer
        return api_serializers.MemberSerializer

    def destroy(self, request, *args, **kwargs):
        member = self.get_object()
        if member.cluster.owner == member.user:
            raise exceptions.ValidationError("cannot delete membership with this cluster as you own it.")
        return super(MemberPutRetrieveUpdateDeleteView, self).destroy(request, *args, **kwargs)

class PutAsCreateMixin(object):
    """
    The following mixin class may be used in order to support PUT-as-create
    behavior for incoming requests.
    """

    def update(self, request, **kwargs):
        partial = kwargs.pop('partial', False)
        instance = self.get_object_or_none()
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        serializer.is_valid(raise_exception=True)

        if instance is None:
            if not self.lookup_fields:
                lookup_url_kwarg = self.lookup_url_kwarg or self.lookup_field
                lookup_value = self.kwargs[lookup_url_kwarg]
                extra_kwargs = {self.lookup_field: lookup_value}
            else:
                # add kwargs for additional fields
                extra_kwargs = {field: self.kwargs[field] for field in self.lookup_fields if self.kwargs[field]}
            serializer.save(**extra_kwargs)
            return Response(serializer.data, status=201)

        serializer.save()
        return Response(serializer.data)

    def partial_update(self, request, *args, **kwargs):
        kwargs['partial'] = True
        return self.update(request, *args, **kwargs)

    def get_object_or_none(self):
        try:
            return self.get_object()
        except Http404:
            if self.request.method == 'PUT':
                # For PUT-as-create operation, we need to ensure that we have
                # relevant permissions, as if this was a POST request.  This
                # will either raise a PermissionDenied exception, or simply
                # return None.
                self.check_permissions(clone_request(self.request, 'POST'))
            else:
                # PATCH requests where the object does not exist should still
                # return a 404 response.
                raise


class MultipleFieldLookupMixin(object):
    """
    Apply this mixin to any view or viewset to get multiple field filtering
    based on a `lookup_fields` attribute, instead of the default single field filtering.
    """

    def get_object(self):
        queryset = self.get_queryset()  # Get the base queryset
        queryset = self.filter_queryset(queryset)  # Apply any filter backends
        filter = {}
        for field in self.lookup_fields:
            if self.kwargs[field]:  # Ignore empty fields.
                filter[field] = self.kwargs[field]
        obj = get_object_or_404(queryset, **filter)  # Lookup the object
        self.check_object_permissions(self.request, obj)
        return obj

path('clusters/<int:cluster>/members/<int:user>/', views.MemberPutRetrieveUpdateDeleteView.as_view())

'clusters/3/members/2/'

in __set__
    self.field.remote_field.model._meta.object_name,
ValueError: Cannot assign "2": "Member.user" must be a "User" instance.